Motor having improved properties

ABSTRACT

The present invention describes a motor designed for Fuel compatibility comprising a lubricant composition comprises at least one ester group containing polymer having a high polarity.

The present application relates to a motor having improved properties.Furthermore the present invention describes a use of polymers to improvethe emulsion stability of lubricants.

Fuels are nowadays generally obtained from fossil sources. However,these resources are limited, so that replacements are being sought.Therefore, interest is rising in renewable raw materials which can beused to produce fuels.

Alternate fuels for transportation, such as methanol, ethanol, etc. havebeen studied by the automotive industry for a number of years. Whilesuch fuels offer some advantages of reduced engine emissions, their useis accompanied by a number of deficiencies and limitations which must beaddressed if they are to become viable alternatives to gasoline.

In view of the declining ecological quality and decreasing world crudeoil reserves, the use of pure bio alcohols, such as ethanol (E100) ormethanol (M100) has been an important target in many countries. However,many issues, ranging from different combustion characteristic tocorrosion of seal materials, have been reported as hindrances to the useof bio alcohols as a replacement for fossil gasoline. Another majorobstacle is the high amount of water formed by the combustion process orbeing present based on the production process of the alcohol incomparison to conventional gasoline.

The water formed during combustion, along with alcohol which bypassesthe piston rings or is carried away by the blow-by gases, tends toaccumulate in the oil.

The alcohol and water may accumulate in the lubricating oil resultingfrom the use of such alternate fuels increase corrosion and wearproblems in engines using such alternate fuels, especially alcohol.

The problems mentioned above depend of the type of use of the passengercar. Using the car on very short range circles lead to very criticalproblems resulting in short time lubricant changes. Furthermore, theissues are more critical to motors having a high sophisticated emissioncontrol system and further technical approaches for fuel savings. Themore sophisticated the motor the more sensitive the motor on lubricantdecline, e.g. based on undue water content.

Lubricant decline, especially high water content and phase separationhave detrimental effects on various properties of the motor. These areespecially critical for motors having Flex Fuel compatibility. Highwater content usually may cause problems regarding cold start and coldrun characteristics of the motor. In addition thereto, the life time andthe fuel consumption of the motor are negatively influenced by a highwater content of the lubricant.

There have been many attempts to date to improve cold start and cold runcharacteristics of the motors by engineering techniques and newfacilities. However, these options are connected with disadvantagesbased on high costs and the fact that usually only the latest cars canbenefit from such improvements. Therefore, further opportunities toimprove the cold start and cold run characteristics, the life time andthe fuel consumption of the motor would be helpful.

The use of ester group containing polymers is known in prior art, e.g.U.S. Pat. No. 4,290,925 described grafted polymethacrylates containingN-vinyl-2-pyrrolidone which are useful for preparing stable emulsions ofolefin copolymers.

U.S. Pat. No. 4,057,623 described copolymers of alkyl methacrylates andN-vinyl-2-pyrrolidone which are useful for producing water-in-oilemulsions for cosmetic applications. U.S. Pat. No. 3,519,565 describedcopolymers of alkyl methacrylates and N-vinylthiopyrrolidone which areuseful for reducing engine sludge and varnish.

In addition thereto GB2307916A discloses that multifunctional olefiniccopolymer viscosity index improver with dispersant properties incombination with further additives can improve the emulsion stability oflubricants. However, no hints are mention with regard to ester groupcontaining polymer having a high polarity. In addition thereto, nospecific motor type has been disclosed.

In view of the prior art, it was thus an object of the present inventionto provide a solution which is not limited to new motor designs and canbe applied to existing flex-fuel motors. Especially the cold start andcold run characteristics of flex-fuel motors should be improved.Furthermore, the improvement of life time and fuel consumption is afurther object of the present invention.

These improvements should be achieved without environmental drawbacks.

It was a further object of the invention to provide additives forlubricating oils which provide improved cold start and cold runcharacteristics of flex-fuel motors. In addition thereto the additiveshould improve the life time and the fuel consumption of flex-fuelmotors.

Furthermore, the additives should be producible in a simple andinexpensive manner, and especially commercially available componentsshould be used. In this context, they should be producible on theindustrial scale without new plants or plants of complicatedconstruction being required for this purpose.

It was a further aim of the present invention to provide an additivewhich brings about a multitude of desirable properties in the lubricant.This can minimize the number of different additives.

Furthermore, the additive should not exhibit any adverse effects on thefuel consumption or the environmental compatibility of the lubricant.

Moreover, the additive should improve the emulsion stability oflubricating oils comprising a high amount of water.

These objects and also further objects which are not stated explicitlybut are immediately derivable or discernible from the connectionsdiscussed herein by way of introduction are achieved by a motor havingall features of claim 1. Appropriate modifications to the inventivemotor are protected in the claims referring back to claim 1. With regardto the use, claim 22 provides a solution to the underlying problem.

The present invention accordingly provides a motor designed for FlexFuel compatibility comprising a lubricant composition, characterized inthat the lubricant composition comprises at least one ester groupcontaining polymer having a high polarity.

It is thus possible in an unforeseeable manner to provide a motordesigned for Flex Fuel compatibility having an improved cold start andcold run characteristics. In addition thereto, the motor of the presentinvention shows an enhanced life time and lowered fuel consumption.

In addition thereto, the motor of the present invention enables extendedoil change intervals. Thus the motor provides significant improvementsin economic aspects based on lower amounts of motor oil based on aspecific mileage.

Moreover, the solution presented by the present invention is not limitedto new motor designs and can be applied to existing flex-fuel motors.

Furthermore, the motor of the present invention can have a very highcompression without being detrimental effected regarding the cold startand cold run characteristics and life time and the fuel consumption offlex-fuel motors.

Furthermore, the additives used in order to obtain a lubricant beingable to solve the problems mentioned above can be prepared in a simpleand inexpensive manner, and it is possible to use commercially availablecomponents in particular. At the same time, production is possible onthe industrial scale, without new plants or plants of complexconstruction being required for that purpose.

Furthermore, the polymers for use in accordance with the inventionexhibit a particularly favorable profile of properties. For instance,the polymers can be configured so as to be surprisingly shear-stable,such that the lubricants have a very long service life. In addition, theadditive for use in accordance with the invention may bring about amultitude of desirable properties in the lubricant. For example, it ispossible to produce lubricants with outstanding low-temperatureproperties or viscosity properties, which comprise the present polymerscomprising ester groups. This allows the number of different additivesto be minimized. Furthermore, the present polymers comprising estergroups are compatible with many additives. This allows the lubricants tobe adjusted to a wide variety of different requirements.

Furthermore, the additives for use do not exhibit any adverse effects onfuel consumption or the environmental compatibility of the lubricant.

Surprisingly, present polymers comprising ester groups improve theemulsion stability of lubricating oils comprising a high amount ofwater.

The present invention provides a new motor designed for Flex Fuelcompatibility. These motors are usually part of flex-fuel vehicles.

A flexible-fuel vehicle (FFV) or dual-fuel vehicle (colloquially calleda flex-fuel vehicle) is an alternative fuel vehicle with an internalcombustion engine designed to run on more than one fuel, usuallygasoline blended with either ethanol or methanol fuel, and both fuelsare stored in the same common tank. Flex-fuel engines are capable ofburning any proportion of the resulting blend in the combustion chamberas fuel injection and spark timing are adjusted automatically accordingto the actual blend detected by electronic sensors. Flex-fuel vehiclesare distinguished from bi-fuel vehicles, where two fuels are stored inseparate tanks and the engine runs on one fuel at a time, for example,compressed natural gas (CNG), liquefied petroleum gas (LPG), orhydrogen.

Though technology exists to allow ethanol FFVs to run on any mixture ofgasoline and ethanol, from pure gasoline up to 100% ethanol (E100),North American and European flex-fuel vehicles are optimized to run on amaximum blend of 15% gasoline with 85% anhydrous ethanol (called E85fuel). This limit in the ethanol content is set to reduce ethanolemissions at low temperatures and to avoid cold starting problems duringcold weather, at temperatures lower than 11° C. (52° F.). The alcoholcontent is reduced during the winter in regions where temperatures fallbelow 0° C. (32° F.) to a winter blend of E70 in the U.S. or to E75 inSweden from November until March. Brazilian flex fuel vehicles areoptimized to run on any mix of E20-E25 gasoline and up to 100% hydrousethanol fuel (E100). The Brazilian flex vehicles are built-in with asmall gasoline reservoir for cold starting the engine when temperaturesdrop below 15° C. (59° F.).

Preferably, the motor of the present invention is designed to fuelscomprising at least 5%, especially at least 10%, particularly 20%, moreespecially at least 50% and more preferably at least 80% by volume ofalcohol, e.g. methanol and/or ethanol. Furthermore, the motor of thepresent invention is preferably designed to fuels comprising at least5%, especially at least 10%, particularly 20%, more especially at least50% and more preferably at least 80% by volume of gasoline.

Preferably, the motor comprises a compression of at least 10:1, morepreferably at least 12:1.

According to a special aspect of the present invention, the motor maycomprise a fuel injection pump.

Unforeseeable advantages can be achieved by a motor comprising a multivalve technique.

Furthermore, the motor of the present invention may comprise an exhaustgas recirculation and/or a secondary-air system.

Preferably, the motor comprises an engine management for optimization ofthe fuel injection and the spark timing.

Preferred motor of the present invention meet the requirements ofexhaust emission standard Euro 5, more preferably EURO 6 as defined inDirective No. 715/2007/EC.

The motor of the present invention comprises a lubricant compositionincluding at least one ester group containing polymer having a highpolarity.

Polymers comprising ester groups are understood in the context of thepresent invention to mean polymers obtainable by polymerizing monomercompositions which comprise ethylenically unsaturated compounds havingat least one ester group, which are referred to hereinafter as estermonomers. Accordingly, these polymers contain ester groups as part ofthe side chain. These polymers include especially polyalkyl(meth)acrylates (PAMA), polyalkyl fumarates and/or polyalkyl maleates.

Ester monomers are known per se. They include especially(meth)acrylates, maleates and fumarates, which may have differentalcohol radicals. The expression “(meth)acrylates” encompassesmethacrylates and acrylates, and mixtures of the two. These monomers arewidely known.

The polymer comprising ester groups comprises preferably at least 40% byweight, more preferably at least 60% by weight, especially preferably atleast 80% by weight and most preferably at least 90% by weight of repeatunits derived from ester monomers.

Polymers usable in accordance with the invention have a high polarity.Consequently, the polymer may be a statistical copolymer comprising ahigh amount of dispersing repeat units being derived from a dispersingmonomer. Preferably, the statistical copolymer comprises at least 7%,more preferably at least 9% by weight of dispersing repeat units beingderived from a dispersing monomer. In addition thereto, the polymer maybe a graft copolymer having an nonpolar polymer as graft base and andispersing monomer as graft layer. Surprising improvements can beachieved with graft copolymers preferably comprising 0.5 to 10% byweight, especially 0.8 to 7% by weight, more preferably 1 to 5% byweight of dispersing repeat units being derived from at least onedispersing monomer, preferably a heterocyclic vinyl compound.

The term “repeat unit” is widely known in the technical field. Thepresent polymers can preferably be obtained by means of free-radicalpolymerization of monomers. This opens up double bonds to form covalentbonds. Accordingly, the repeat unit arises from the monomers used.

Dispersing monomers are understood to mean especially monomers withfunctional groups, for which it can be assumed that polymers with thesefunctional groups can keep particles, especially soot particles, insolution (cf. R. M. Mortier, S. T. Orszulik (eds.): “Chemistry andTechnology of Lubricants”, Blackie Academic & Professional, London,2^(nd) ed. 1997). These include especially monomers which have boron-,phosphorus-, silicon-, sulfur-, oxygen- and nitrogen-containing groups,preference being given to oxygen- and nitrogen-functionalized monomers.

The nonpolar graft base may comprise a small proportion of dispersingrepeat units, which is preferably less than 20% by weight, morepreferably less than 10% by weight and most preferably less than 5% byweight, based on the weight of the nonpolar graft base. In aparticularly appropriate configuration, the nonpolar graft basecomprises essentially no dispersing repeat units.

The nonpolar graft base of the polymer comprising ester groups may have5 to 100% by weight, especially 20 to 98% by weight, preferably 30 to 95and most preferably 70 to 92% by weight of repeat units derived fromester monomers having 7 to 15 carbon atoms in the alcohol radical.

In a particular aspect, the nonpolar graft base of the polymercomprising ester groups may have 0 to 80% by weight, preferably 0.5 to60% by weight, more preferably 2 to 50% by weight and most preferably 5to 20% by weight of repeat units derived from ester monomers having 16to 40 carbon atoms in the alcohol radical.

In addition, the nonpolar graft base of the polymer comprising estergroups may have 0 to 40% by weight, preferably 0.1 to 30% by weight andmore preferably 0.5 to 20% by weight of repeat units derived from estermonomers having 1 to 6 carbon atoms in the alcohol radical.

The nonpolar graft base of the polymer comprising ester groups comprisespreferably at least 40% by weight, more preferably at least 60% byweight, especially preferably at least 80% by weight and most preferablyat least 90% by weight of repeat units derived from ester monomers.

Mixtures from which the graft base of the useful polymers comprisingester groups or the statistical polymers are obtainable may contain 0 to40% by weight, especially 0.1 to 30% by weight and more preferably 0.5to 20% by weight of one or more ethylenically unsaturated estercompounds of the formula (I)

in which R is hydrogen or methyl, R¹ is a linear or branched alkylradical having 1 to 6 carbon atoms, R² and R³ are each independentlyhydrogen or a group of the formula —COOR′ in which R′ is hydrogen or analkyl group having 1 to 6 carbon atoms.

Examples of component (I) include

(meth)acrylates, fumarates and maleates which derive from saturatedalcohols, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl(meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate,tert-butyl (meth)acrylate and pentyl (meth)acrylate, hexyl(meth)acrylate;cycloalkyl (meth)acrylates such as cyclopentyl (meth)acrylate,cyclohexyl (meth)acrylate;(meth)acrylates which derive from unsaturated alcohols, such as2-propynyl (meth)acrylate, allyl (meth)acrylate and vinyl(meth)acrylate.

The compositions to be polymerized to prepare the graft base or thestatistical polymers preferably contain 5 to 100% by weight, preferably10 to 98% by weight and especially preferably 20 to 95% by weight of oneor more ethylenically unsaturated ester compounds of the formula (II)

in which R is hydrogen or methyl, R⁴ is a linear or branched alkylradical having 7 to 15 carbon atoms, R⁵ and R⁶ are each independentlyhydrogen or a group of the formula —COOR″ in which R″ is hydrogen or analkyl group having 7 to 15 carbon atoms.

Examples of component (II) include:

(meth)acrylates, fumarates and maleates which derive from saturatedalcohols, such as 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate,2-tert-butylheptyl (meth)acrylate, octyl (meth)acrylate,3-isopropylheptyl (meth)acrylate, nonyl (meth)acrylate, decyl(meth)acrylate, undecyl (meth)acrylate, 5-methylundecyl (meth)acrylate,dodecyl (meth)acrylate, 2-methyldodecyl (meth)acrylate, tridecyl(meth)acrylate, 5-methyltridecyl (meth)acrylate, tetradecyl(meth)acrylate, pentadecyl (meth)acrylate;(meth)acrylates which derive from unsaturated alcohols, for exampleoleyl (meth)acrylate;cycloalkyl (meth)acrylates, such as 3-vinylcyclohexyl (meth)acrylate,bornyl (meth)acrylate; and the corresponding fumarates and maleates.

In addition, preferred monomer compositions for preparing the graft baseor the statistical polymers comprise 0 to 80% by weight, preferably 0.5to 60% by weight, more preferably 2 to 50% by weight and most preferably5 to 20% by weight of one or more ethylenically unsaturated estercompounds of the formula (III)

in which R is hydrogen or methyl, R⁷ is a linear or branched alkylradical having 16 to 40, preferably 16 to 30, carbon atoms, R⁸ and R⁹are each independently hydrogen or a group of the formula —COOR′″ inwhich R′″ is hydrogen or an alkyl group having 16 to 40, preferably 16to 30, carbon atoms.

Examples of component (III) include (meth)acrylates which derive fromsaturated alcohols, such as hexadecyl (meth)acrylate, 2-methylhexadecyl(meth)acrylate, heptadecyl (meth)acrylate, 5-isopropylheptadecyl(meth)acrylate, 4-tert-butyloctadecyl (meth)acrylate, 5-ethyloctadecyl(meth)acrylate, 3-isopropyloctadecyl (meth)acrylate, octadecyl(meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate,cetyleicosyl (meth)acrylate, stearyleicosyl (meth)acrylate, docosyl(meth)acrylate and/or eicosyltetratriacontyl (meth)acrylate;

cycloalkyl (meth)acrylates such as 2,4,5-tri-t-butyl-3-vinylcyclohexyl(meth)acrylate, 2,3,4,5-tetra-t-butylcyclohexyl (meth)acrylate;and the corresponding fumarates and maleates.

The ester compounds with a long-chain alcohol radical, especiallycomponents (II) and (III), can be obtained, for example, by reacting(meth)acrylates, fumarates, maleates and/or the corresponding acids withlong-chain fatty alcohols, which generally gives a mixture of esters,for example (meth)acrylates with different long-chain alcohol radicals.These fatty alcohols include Oxo Alcohol® 7911, Oxo Alcohol® 7900, OxoAlcohol® 1100; Alfol® 610, Alfol® 810, Lial® 125 and Nafol® types(Sasol); Alphanol® 79 (ICI); Epal® 610 and Epal® 810 (Afton); Linevol®79, Linevol® 911 and Neodol® 25E (Shell); Dehydad®, Hydrenol® and Lorol®types (Cognis); Acropol® 35 and Exxal® 10 (Exxon Chemicals); Kalcol®2465 (Kao Chemicals).

Among the ethylenically unsaturated ester compounds, the (meth)acrylatesare particularly preferred over the maleates and fumarates, i.e. R², R³,R⁵, R⁶, R⁸ and R⁹ of the formulae (I), (II) and (III) are each hydrogenin particularly preferred embodiments.

The weight ratio of ester monomers of the formula (II) to the estermonomers of the formula (III) may be within a wide range. The ratio ofester compounds of the formula (II) which have 7 to 15 carbon atoms inthe alcohol radical to the ester compounds of the formula (III) whichhave 16 to 40 carbon atoms in the alcohol radical is preferably in therange from 50:1 to 1:30, more preferably in the range from 10:1 to 1:3,especially preferably 5:1 to 1:1.

In addition, the monomer mixture for preparing the graft base or thestatistical polymers may comprise ethylenically unsaturated monomerswhich can be copolymerized with the ethylenically unsaturated estercompounds of the formulae (I), (II) and/or (III).

The preferred comonomers include

vinyl halides, for example vinyl chloride, vinyl fluoride, vinylidenechloride and vinylidene fluoride;styrene, substituted styrenes having an alkyl substituent in the sidechain, for example α-methylstyrene and α-ethylstyrene, substitutedstyrenes having an alkyl substituent on the ring, such as vinyltolueneand p-methylstyrene, halogenated styrenes, for examplemonochlorostyrenes, dichlorostyrenes, tribromostyrenes andtetrabromostyrenes;vinyl and isoprenyl ethers;maleic acid and maleic acid derivatives different from those mentionedunder (I), (II) and (III), for example maleic anhydride, methylmaleicanhydride, maleimide, methylmaleimide;fumaric acid and fumaric acid derivatives different from those mentionedunder (I), (II) and (III).

In addition, monomer mixtures for preparing the graft base may comprisedispersing monomers.

The proportion of comonomers is preferably 0 to 50% by weight, morepreferably 0.1 to 40% by weight and most preferably 0.5 to 20% byweight, based on the weight of the monomer composition for preparing thegraft base or the statistical polymers.

In addition to the graft base, a preferred polymer usable in accordancewith the invention comprises at least one graft layer which comprisesrepeat units derived from dispersing monomers.

Dispersing monomers have been used for some time for functionalizingpolymeric additives in lubricant oils, and are therefore known to thoseskilled in the art (cf. R. M. Mortier, S. T. Orszulik (eds.): “Chemistryand Technology of Lubricants”, Blackie Academic & Professional, London,2^(nd) ed. 1997). Appropriately, it is possible to use especiallyheterocyclic vinyl compounds and/or ethylenically unsaturated, polarester compounds of the formula (IV)

in which R is hydrogen or methyl, X is oxygen, sulfur or an amino groupof the formula —NH— or —NR^(a)— in which R^(a) is an alkyl radicalhaving 1 to 40 and preferably 1 to 4 carbon atoms, R¹⁰ is a radicalwhich comprises 2 to 1000, especially 2 to 100 and preferably 2 to 20carbon atoms and has at least one heteroatom, preferably at least twoheteroatoms, R¹¹ and R¹² are each independently hydrogen or a group ofthe formula —COX′R^(10′) in which X′ is oxygen or an amino group of theformula —NH— or —NR^(a′)— in which R^(a′) is an alkyl radical having 1to 40 and preferably 1 to 4 carbon atoms, and R^(10′) is a radicalcomprising 1 to 100, preferably 1 to 30 and more preferably 1 to 15carbon atoms, as dispersing monomers.

The expression “radical comprising 2 to 1000 carbon” denotes radicals oforganic compounds having 2 to 1000 carbon atoms. Similar definitionsapply for corresponding terms. It encompasses aromatic andheteroaromatic groups, and alkyl, cycloalkyl, alkoxy, cycloalkoxy,alkenyl, alkanoyl, alkoxycarbonyl groups, and also heteroaliphaticgroups. The groups mentioned may be branched or unbranched. In addition,these groups may have customary substituents. Substituents are, forexample, linear and branched alkyl groups having 1 to 6 carbon atoms,for example methyl, ethyl, propyl, butyl, pentyl, 2-methylbutyl orhexyl; cycloalkyl groups, for example cyclopentyl and cyclohexyl;aromatic groups such as phenyl or naphthyl; amino groups, hydroxylgroups, ether groups, ester groups and halides.

According to the invention, aromatic groups denote radicals of mono- orpolycyclic aromatic compounds having preferably 6 to 20 and especially 6to 12 carbon atoms. Heteroaromatic groups denote aryl radicals in whichat least one CH group has been replaced by N and/or at least twoadjacent CH groups have been replaced by S, NH or O, heteroaromaticgroups having 3 to 19 carbon atoms.

Aromatic or heteroaromatic groups preferred in accordance with theinvention derive from benzene, naphthalene, biphenyl, diphenyl ether,diphenylmethane, diphenyldimethylmethane, bisphenone, diphenyl sulfone,thiophene, furan, pyrrole, triazole, oxazole, imidazole, isothiazole,isoxazole, pyrazole, 1,3,4-oxadiazole, 2,5-diphenyl-1,3,4-oxadiazole,1,3,4-thiadiazole, 1,3,4-triazole, 2,5-diphenyl-1,3,4-triazole,1,2,5-triphenyl-1,3,4-triazole, 1,2,4-oxadiazole, 1,2,4-thiadiazole,1,2,4-triazole, 1,2,3-triazole, 1,2,3,4-tetrazole, benzo[b]thiophene,benzo[b]furan, indole, benzo[c]thiophene, benzo[c]furan, isoindole,benzoxazole, benzothiazole, benzimidazole, benzisoxazole,benzisothiazole, benzopyrazole, benzothiadiazole, benzotriazole,dibenzofuran, dibenzothiophene, carbazole, pyridine, bipyridine,pyrazine, pyrazole, pyrimidine, pyridazine, 1,3,5-triazine,1,2,4-triazine, 1,2,4,5-triazine, tetrazine, quinoline, isoquinoline,quinoxaline, quinazoline, cinnoline, 1,8-naphthyridine,1,5-naphthyridine, 1,6-naphthyridine, 1,7-naphthyridine, phthalazine,pyridopyrimidine, purine, pteridine or quinolizine, 4H-quinolizine,diphenyl ether, anthracene, benzopyrrole, benzoxathiadiazole,benzoxadiazole, benzo-pyridine, benzopyrazine, benzopyrazidine,benzopyrimidine, benzotriazine, indolizine, pyridopyridine,imidazopyrimidine, pyrazinopyrimidine, carbazole, aciridine, phenazine,benzoquinoline, phenoxazine, phenothiazine, acridizine, benzopteridine,phenanthroline and phenanthrene, each of which may also optionally besubstituted.

The preferred alkyl groups include the methyl, ethyl, propyl, isopropyl,1-butyl, 2-butyl, 2-methylpropyl, tert-butyl radical, pentyl,2-methylbutyl, 1,1-dimethylpropyl, hexyl, heptyl, octyl,1,1,3,3-tetramethylbutyl, nonyl, 1-decyl, 2-decyl, undecyl, dodecyl,pentadecyl and the eicosyl group.

The preferred cycloalkyl groups include the cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl and the cyclooctyl group, each ofwhich is optionally substituted with branched or unbranched alkylgroups.

The preferred alkanoyl groups include the formyl, acetyl, propionyl,2-methylpropionyl, butyryl, valeroyl, pivaloyl, hexanoyl, decanoyl andthe dodecanoyl group.

The preferred alkoxycarbonyl groups include the methoxycarbonyl,ethoxycarbonyl, propoxycarbonyl, butoxy-carbonyl, tert-butoxycarbonyl,hexyloxycarbonyl, 2-methylhexyloxycarbonyl, decyloxycarbonyl ordodecyl-oxycarbonyl group.

The preferred alkoxy groups include alkoxy groups whose hydrocarbonradical is one of the aforementioned preferred alkyl groups.

The preferred cycloalkoxy groups include cycloalkoxy groups whosehydrocarbon radical is one of the aforementioned preferred cycloalkylgroups.

The preferred heteroatoms which are present in the R¹⁰ radical includeoxygen, nitrogen, sulfur, boron, silicon and phosphorus, preferencebeing given to oxygen and nitrogen.

The R¹⁰ radical comprises at least one, preferably at least two,preferentially at least three, heteroatoms.

The R¹⁰ radical in ester compounds of the formula (IV) preferably has atleast 2 different heteroatoms. In this case, the R¹⁰ radical in at leastone of the ester compounds of the formula (IV) may comprise at least onenitrogen atom and at least one oxygen atom.

Examples of ethylenically unsaturated, polar ester compounds of theformula (IV) include aminoalkyl (meth)acrylates, aminoalkyl(meth)acrylamides, hydroxyalkyl (meth)acrylates, heterocyclic(meth)acrylates and/or carbonyl-containing (meth)acrylates.

The hydroxyalkyl (meth)acrylates include

-   2-hydroxypropyl (meth)acrylate,-   3,4-dihydroxybutyl (meth)acrylate,-   2-hydroxyethyl (meth)acrylate,-   3-hydroxypropyl (meth)acrylate,-   2,5-dimethyl-1,6-hexanediol (meth)acrylate and-   1,10-decanediol (meth)acrylate.

Appropriate carbonyl-containing (meth)acrylates include, for example,

-   2-carboxyethyl (meth)acrylate,-   carboxymethyl (meth)acrylate,-   oxazolidinylethyl (meth)acrylate,-   N-(methacryloyloxy)formamide,-   acetonyl (meth)acrylate,-   mono-2-(meth)acryloyloxyethyl succinate,-   N-(meth)acryloylmorpholine,-   N-(meth)acryloyl-2-pyrrolidinone,-   N-(2-(meth)acryloyloxyethyl)-2-pyrrolidinone,-   N-(3-(meth)acryloyloxypropyl)-2-pyrrolidinone,-   N-(2-(meth)acryloyloxypentadecyl)-2-pyrrolidinone,-   N-(3-(meth)acryloyloxyheptadecyl)-2-pyrrolidinone and-   N-(2-(meth)acryloyloxyethyl)ethyleneurea.-   2-Acetoacetoxyethyl (meth)acrylate

The heterocyclic (meth)acrylates include

-   2-(1-imidazolyl)ethyl (meth)acrylate,-   2-(4-morpholinyl)ethyl (meth)acrylate and-   1-(2-(meth)acryloyloxyethyl)-2-pyrrolidone.

Of particular interest are additionally aminoalkyl (meth)acrylates andaminoalkyl (meth)acrylatamides, for example

-   dimethylaminopropyl (meth)acrylate,-   dimethylaminodiglykol (meth)acrylate,-   dimethylaminoethyl (meth)acrylate,-   dimethylaminopropyl (meth)acrylamide,-   3-diethylaminopentyl(meth)acrylate and-   3-dibutylaminohexadecyl (meth)acrylate.

In addition, it is possible to use phosphorus-, boron- and/orsilicon-containing (meth)acrylates to prepare the polar segments D, suchas

-   2-(dimethylphosphato)propyl (meth)acrylate,-   2-(ethylenephosphito)propyl (meth)acrylate,-   dimethylphosphinomethyl (meth)acrylate,-   dimethylphosphonoethyl (meth)acrylate,-   diethyl(meth)acryloyl phosphonate,-   dipropyl(meth)acryloyl phosphate, 2-(dibutylphosphono)ethyl    (meth)acrylate,-   2,3-butylene(meth)acryloylethyl borate,-   methyldiethoxy(meth)acryloylethoxysilane,-   diethylphosphatoethyl (meth)acrylate.

According to a very preferred embodiment heterocyclic vinyl compoundsare used as dispersing monomers. Surprisingly, the heterocyclic vinylcompounds show improved properties in view of other dispersing monomers.

The preferred heterocyclic vinyl compounds include 2-vinylpyridine,3-vinylpyridine, 2-methyl-5-vinylpyridine, 3-ethyl-4-vinylpyridine, 2,3dimethyl-5-vinylpyridine, vinylpyrimidine, vinylpiperidine,9-vinylcarbazole, 3-vinylcarbazole, 4-vinylcarbazole, 1-vinylimidazole,N-vinylimidazole, 2-methyl-1-vinylimidazole, N-vinylpyrrolidone,2-vinylpyrrolidone, N-vinylpyrrolidine, 3-vinylpyrrolidine,N-vinylcaprolactam, N-vinylbutyrolactam, vinyloxolane, vinylfuran,vinylthiophene, vinylthiolane, vinylthiazoles and hydrogenatedvinylthiazoles, vinyloxazoles and hydrogenated vinyloxazoles, particularpreference being given to using N-vinylimidazole and N-vinylpyrrolidonefor functionalization.

The monomers detailed above can be used individually or as a mixture.

Of particular interest are especially polymers which comprise estergroups and are obtained using 2-hydroxypropyl methacrylate,2-hydroxyethyl methacrylate, mono-2-methacryloyloxyethyl succinate,N-(2-methacryloyloxyethyl)ethyleneurea, 2-acetoacetoxyethylmethacrylate, 2-(4-morpholinyl)ethyl methacrylate, dimethylaminodiglycolmethacrylate, dimethylaminoethyl methacrylate and/ordimethylaminopropylmethacrylamide.

Special improvements can be achieved with ester groups comprise polymersbeing obtained using N-vinyl-2-pyrrolidine and/or N-vinyl-2-pyrrolidone.

In addition to the dispersing monomers, a composition for preparing thegraft layer may also comprise non-dispersing monomers which have beendetailed above. These include especially ethylenically unsaturated estercompounds of the formulae (I), (II) and/or (III).

The proportion of dispersing repeat units, based on the weight of thepolymers comprising ester groups, is preferably in the range from 0.5%by weight to 20% by weight, more preferably in the range from 1.5% byweight to 15% by weight and most preferably in the range from 2.5% byweight to 10% by weight. At the same time, these repeat units preferablyform a segment-like structure within the polymer comprising estergroups, such that preferably at least 70% by weight, more preferably atleast 80% by weight, based on the total weight of the dispersing repeatunits, are part of a graft layer.

The present invention describes polymers which preferably have a highoil solubility. The term “oil-soluble” means that a mixture of a baseoil and a polymer comprising ester groups is preparable withoutmacroscopic phase formation, which has at least 0.1% by weight,preferably at least 0.5% by weight, of the polymers. The polymer may bepresent in dispersed and/or dissolved form in this mixture. The oilsolubility depends especially on the proportion of the lipophilic sidechains and on the base oil. This property is known to those skilled inthe art and can be adjusted readily for the particular base oil via theproportion of lipophilic monomers.

Of particular interest, among others, are polymers which comprise estergroups and preferably have a weight-average molecular weight M_(w) inthe range from 7500 to 1 000 000 g/mol, more preferably 10 000 to 600000 g/mol and most preferably 15 000 to 80 000 g/mol.

The number-average molecular weight M_(n) may preferably be in the rangefrom 5000 to 800 000 g/mol, more preferably 7500 to 500 000 g/mol andmost preferably 10 000 to 80 000 g/mol.

According to a special embodiment of the present invention, the estergroup containing polymer, preferably a polyalkyl(meth)acrylat may have aweight-average molecular weight M_(w) in the range from 2000 to 1 000000 g/mol, especially from 20 000 to 800 000 g/mol, more preferably 40000 to 500 000 g/mol and most preferably 60 000 to 250 000 g/mol.

According to a further aspect of the present invention, the ester groupcontaining polymer, preferably a polyalkyl(meth)acrylat may have anumber average molecular weight M_(n) in the range from 2 000 to 100 000g/mol, especially from 4 000 to 60 000 g/mol and most preferably 5 000to 30 000 g/mol.

Polymers having a high molecular weight are especially useful asviscosity index improvers. Polymers having a low molecular weight areespecially useful as pour point depressants and flow improvers.

Additionally appropriate are polymers which comprise ester groups andwhose polydispersity index M_(w)/M_(n) is in the range from 1 to 5, morepreferably in the range from 1.05 to 4. The number-average andweight-average molecular weights can be determined by known processes,for example gel permeation chromatography (GPC).

According to a preferred embodiment of the present invention, the estergroup containing polymer has a —CO—NR₂-peak in the range of 1689 to 1697cm⁻¹, more preferably in the range of 1689 to 1692 cm¹ as measured byFTIR spectroscopy (25° C.)

The polymer comprising ester groups may have a variety of structures.Preferably, the polymer may especially be present as a graft copolymer.

The polymers comprising ester groups for use in accordance with theinvention can be obtained in various ways. A preferred process consistsin free-radical graft copolymerization which is known per se, wherein,for example, a nonpolar graft base is obtained in a first step, ontowhich dispersing monomers are grafted in a second step.

Therefore, according to a preferred embodiment, the ester groupcontaining polymer preferably is a graft copolymer having an nonpolaralkyl (meth)acrylate polymer as graft base and an dispersing monomer asgraft layer.

Customary free-radical polymerization, which is especially suitable forpreparing graft copolymers, is detailed in K. Matyjaszewski, T. P.Davis, Handbook of Radical Polymerization, Wiley Interscience, Hoboken2002. In general, a polymerization initiator and a chain transferer areused for that purpose.

The usable initiators include the azo initiators widely known in thetechnical field, such as AIBN and 1,1-azobiscyclohexanecarbonitrile, andalso peroxy compounds such as methyl ethyl ketone peroxide,acetylacetone peroxide, dilauryl peroxide, tert-butylper-2-ethylhexanoate, ketone peroxide, tert-butyl peroctoate, methylisobutyl ketone peroxide, cyclohexanone peroxide, dibenzoyl peroxide,tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl-carbonate,2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane, tert-butylperoxy-2-ethylhexanoate, tert-butyl peroxy-3,5,5-trimethylhexanoate,dicumyl peroxide, 1,1-bis(tert-butylperoxy)cyclohexane,1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, cumylhydroperoxide, tert-butyl hydroperoxide, bis(4-tert-butylcyclohexyl)peroxydicarbonate, mixtures of two or more of the aforementionedcompounds with one another, and mixtures of the aforementioned compoundswith compounds which have not been mentioned but can likewise form freeradicals. Suitable chain transferers are in particular oil-solublemercaptans, for example n-dodecyl mercaptan or 2-mercaptoethanol, orelse chain transferers from the class of the terpenes, for exampleterpinolene.

The polymerization may be carried out at standard pressure, reducedpressure or elevated pressure. The polymerization temperature too isuncritical. However, it is generally in the range of −20°-200° C.,preferably 50°-150° C. and more preferably 80°-130° C.

The polymerization may be carried out with or without solvent. The termsolvent is to be understood here in a broad sense. The solvent isselected according to the polarity of the monomers used, preferencebeing given to using 100N oil, relatively light gas oil and/or aromatichydrocarbons, for example toluene or xylene.

In addition to the ester group containing polymer the lubricant used inthe motor of the present invention includes base oil. Preferred baseoils include especially mineral oils, synthetic oils and natural oils.

Mineral oils are known per se and commercially available. They aregenerally obtained from mineral oil or crude oil by distillation and/orrefining and optionally further purification and finishing processes,the term mineral oil including in particular the higher-boilingfractions of crude or mineral oil. In general, the boiling point ofmineral oil is higher than 200° C., preferably higher than 300° C., at5000 Pa. The production by low-temperature carbonization of shale oil,coking of bituminous coal, distillation of brown coal with exclusion ofair, and also hydrogenation of bituminous or brown coal is likewisepossible. Accordingly, mineral oils have, depending on their origin,different proportions of aromatic, cyclic, branched and linearhydrocarbons.

In general, a distinction is drawn between paraffin-base, naphthenic andaromatic fractions in crude oils or mineral oils, in which the termparaffin-base fraction represents longer-chain or highly branchedisoalkanes, and naphthenic fraction represents cycloalkanes. Inaddition, mineral oils, depending on their origin and finishing, havedifferent fractions of n-alkanes, isoalkanes having a low degree ofbranching, known as mono-methyl-branched paraffins, and compounds havingheteroatoms, in particular O, N and/or S, to which a degree of polarproperties are attributed. However, the assignment is difficult, sinceindividual alkane molecules may have both long-chain branched groups andcycloalkane radicals, and aromatic parts. For the purposes of thepresent invention, the assignment can be effected to DIN 51 378, forexample. Polar fractions can also be determined to ASTM D 2007.

The proportion of n-alkanes in preferred mineral oils is less than 3% byweight, the fraction of O-, N- and/or S-containing compounds less than6% by weight. The fraction of the aromatics and of themono-methyl-branched paraffins is generally in each case in the rangefrom 0 to 40% by weight. In one interesting aspect, mineral oilcomprises mainly naphthenic and paraffin-base alkanes which havegenerally more than 13, preferably more than 18 and most preferably morethan 20 carbon atoms. The fraction of these compounds is generally 60%by weight, preferably 80% by weight, without any intention that thisshould impose a restriction. A preferred mineral oil contains 0.5 to 30%by weight of aromatic fractions, 15 to 40% by weight of naphthenicfractions, 35 to 80% by weight of paraffin-base fractions, up to 3% byweight of n-alkanes and 0.05 to 5% by weight of polar compounds, basedin each case on the total weight of the mineral oil.

An analysis of particularly preferred mineral oils, which was effectedby means of conventional processes such as urea separation and liquidchromatography on silica gel, shows, for example, the followingconstituents, the percentages relating to the total weight of theparticular mineral oil used:

n-alkanes having approx. 18 to 31 carbon atoms:0.7-1.0%,slightly branched alkanes having 18 to 31 carbon atoms:1.0-8.0%,aromatics having 14 to 32 carbon atoms:0.4-10.7%,iso- and cycloalkanes having 20 to 32 carbon atoms:60.7-82.4%,polar compounds:0.1-0.8%,loss:6.9-19.4%.

An improved class of mineral oils (reduced sulfur content, reducednitrogen content, higher viscosity index, lower pour point) results fromhydrogen treatment of the mineral oils (hydroisomerization,hydrocracking, hydrotreatment, hydrofinishing). In the presence ofhydrogen, this essentially reduces aromatic components and builds upnaphthenic components.

Valuable information with regard to the analysis of mineral oils and alist of mineral oils which have a different composition can be found,for example, in T. Mang, W. Dresel (eds.): “Lubricants and Lubrication”,Wiley-VCH, Weinheim 2001; R. M. Mortier, S. T. Orszulik (eds.):“Chemistry and Technology of Lubricants”, Blackie Academic &Professional, London, 2^(nd) ed. 1997; or J. Bartz: “Additive fürSchmierstoffe”, Expert-Verlag, Renningen-Malmsheim 1994.

Synthetic oils include organic esters, for example diesters andpolyesters, polyalkylene glycols, polyethers, synthetic hydrocarbons,especially polyolefins, among which preference is given topolyalphaolefins (PAOs), silicone oils and perfluoroalkyl ethers. Inaddition, it is possible to use synthetic base oils originating from gasto liquid (GTL), coal to liquid (CTL) or biomass to liquid (BTL)processes. They are usually somewhat more expensive than the mineraloils, but have advantages with regard to their performance.

Natural oils are animal or vegetable oils, for example neatsfoot oils orjojoba oils.

Base oils for lubricant oil formulations are divided into groupsaccording to API (American Petroleum Institute). Mineral oils aredivided into group I (non-hydrogen-treated) and, depending on the degreeof saturation, sulfur content and viscosity index, into groups II andIII (both hydrogen-treated). PAOs correspond to group IV. All other baseoils are encompassed in group V.

These lubricant oils may also be used as mixtures and are in many casescommercially available.

The concentration of the polymers comprising ester groups in thelubricant oil composition is preferably in the range of 0.01 to 30% byweight, more preferably in the range of 0.1-20% by weight and mostpreferably in the range of 0.5-10% by weight, based on the total weightof the composition.

In addition to the polymers comprising ester groups for use inaccordance with the invention, the lubricant oil compositions detailedhere may also comprise further additives. These additives include VIimprovers, pour point improvers and DI additives (dispersants,detergents, defoamers, corrosion inhibitors, antioxidants, antiwear andextreme pressure additives, friction modifiers).

The additionally usable VI improvers include especially polyalkyl(meth)acrylates having 1 to 30 carbon atoms in the alcohol group (PAMA;partly N/O-functional with advantageous additional properties asdispersants, antiwear additives and/or friction modifiers), which differfrom the copolymers detailed in claim 1, and poly(iso)butenes (PIB),fumarate-olefin copolymers, styrene-maleate copolymers, hydrogenatedstyrene-diene copolymers (HSD) and olefin copolymers (OCP).

The pour point improvers include especially polyalkyl (meth)acrylates(PAMA) having 1 to 30 carbon atoms in the alcohol group.

Compilations of VI improvers and pour point improvers for lubricant oilsare also detailed in T. Mang, W. Dresel (eds.): “Lubricants andLubrication”, Wiley-VCH, Weinheim 2001: R. M. Mortier, S. T. Orszulik(eds.): “Chemistry and Technology of Lubricants”, Blackie Academic &Professional, London, 2nd ed. 1997; or J. Bartz: “Additive fürSchmierstoffe”, Expert-Verlag, Renningen-Malmsheim 1994.

Appropriate dispersants include poly(isobutylene) derivatives, e.g.poly(isobutylene)succinimides (PIBSIs); ethylene-propylene oligomerswith N/O functionalities.

The preferred detergents include metal-containing compounds, for examplephenoxides; salicylates; thio-phosphonates, especiallythiopyrophosphonates, thio-phosphonates and phosphonates; sulfonates andcarbonates. As metals, these compounds may comprise especially calcium,magnesium and barium. These compounds may be used preferably in neutralor overbased form.

Of particular interest are additionally defoamers, which are in manycases divided into silicone-containing and silicone-free defoamers. Thesilicone-containing defoamers include linear poly(dimethylsiloxane) andcyclic poly(dimethylsiloxane). The silicone-free defoamers which may beused are in many cases polyethers, for example poly(ethylene glycol) ortributyl phosphate.

In a particular embodiment, the inventive lubricant oil compositions maycomprise corrosion inhibitors. These are in many cases divided intoantirust additives and metal passivators/deactivators. The antirustadditives used may, inter alia, be sulfonates, for examplepetroleumsulfonates or (in many cases overbased) syntheticalkylbenzenesulfonates, e.g. dinonylnaphthenesulfonates; carboxylic acidderivatives, for example lanolin (wool fat), oxidized paraffins, zincnaphthenates, alkylated succinic acids, 4-nonylphenoxy-acetic acid,amides and imides (N-acylsarcosine, imidazoline derivatives);amine-neutralized mono- and dialkyl phosphates; morpholine,dicyclohexylamine or diethanolamine. The metal passivators/deactivatorsinclude benzotriazole, tolyltriazole, 2-mercaptobenzothiazole,dialkyl-2,5-dimercapto-1,3,4-thiadiazole;N,N′-disalicylideneethylenediamine, N,N′-disalicylidenepropylenediamine;zinc dialkyldithiophosphates and dialkyl dithiocarbamates.

A further preferred group of additives is that of antioxidants. Theantioxidants include, for example, phenols, for example2,6-di-tert-butylphenol (2,6-DTB), butylated hydroxytoluene (BHT),2,6-di-tert-butyl-4-methylphenol,4,4′-methylenebis(2,6-di-tert-butylphenol); aromatic amines, especiallyalkylated diphenylamines, N-phenyl-1-naphthylamine (PNA), polymeric2,2,4-trimethyldihydroquinone (TMQ); compounds containing sulfur andphosphorus, for example metal dithiophosphates, e.g. zincdithiophosphates (ZnDTP), “OOS triesters”=reaction products ofdithiophosphoric acid with activated double bonds from olefins,cyclopentadiene, norbornadiene, α-pinene, polybutene, acrylic esters,maleic esters (ashless on combustion); organosulfur compounds, forexample dialkyl sulfides, diaryl sulfides, polysulfides, modifiedthiols, thiophene derivatives, xanthates, thioglycols, thioaldehydes,sulfur-containing carboxylic acids; heterocyclic sulfur/nitrogencompounds, especially dialkyldimercaptothiadiazoles,2-mercaptobenzimidazoles; zinc and methylenebis(dialkyldithiocarbamate); organophosphorus compounds, for exampletriaryl and trialkyl phosphites; organocopper compounds and overbasedcalcium- and magnesium-based phenolates and salicylates.

The preferred antiwear (AW) and extreme pressure (EP) additives includephosphorus compounds, for example trialkyl phosphates, triarylphosphates, e.g. tricresyl phosphate, amine-neutralized mono- anddialkyl phosphates, ethoxylated mono- and dialkyl phosphates,phosphites, phosphonates, phosphines; compounds containing sulfur andphosphorus, for example metal dithiophosphates, e.g. zincC₃₋₁₂dialkyldithiophosphates (ZnDTPs), ammonium dialkyldithiophosphates,antimony dialkyldithiophosphates, molybdenum dialkyldithiophosphates,lead dialkyldithiophosphates, “OOS triesters”=reaction products ofdithiophosphoric acid with activated double bonds from olefins,cyclopentadiene, norbornadiene, α-pinene, polybutene, acrylic esters,maleic esters, triphenylphosphorothionate (TPPT); compounds containingsulfur and nitrogen, for example zinc bis(amyl dithiocarbamate) ormethylenebis(di-n-butyl dithiocarbamate); sulfur compounds containingelemental sulfur and H₂S-sulfurized hydrocarbons (diisobutylene,terpene); sulfurized glycerides and fatty acid esters; overbasedsulfonates; chlorine compounds or solids such as graphite or molybdenumdisulfide.

A further preferred group of additives is that of friction modifiers.The friction modifiers used may include mechanically active compounds,for example molybdenum disulfide, graphite (including fluorinatedgraphite), poly(trifluoroethylene), polyamide, polyimide; compoundswhich form adsorption layers, for example long-chain carboxylic acids,fatty acid esters, ethers, alcohols, amines, amides, imides; compoundswhich form layers through tribochemical reactions, for example saturatedfatty acids, phosphoric acid and thiophosphoric esters, xanthogenates,sulfurized fatty acids; compounds which form polymer-like layers, forexample ethoxylated dicarboxylic acid partial esters, dialkylphthalates, methacrylates, unsaturated fatty acids, sulfurized olefinsor organometallic compounds, for example molybdenum compounds(molybdenum dithiophosphates and molybdenum dithiocarbamates MoDTC) andtheir combinations with ZnDTPs, copper-containing organic compounds.

Some of the additives detailed above may fulfill multiple functions.ZnDTP, for example, is primarily an antiwear additive and extremepressure additive, but also has the character of an antioxidant andcorrosion inhibitor (here: metal passivator/deactivator).

The additives detailed above are described in more detail, inter alia,in T. Mang, W. Dresel (eds.): “Lubricants and Lubrication”, Wiley-VCH,Weinheim 2001; J. Bartz: “Additive für Schmierstoffe”, Expert-Verlag,Renningen-Malmsheim 1994; R. M. Mortier, S. T. Orszulik (eds.):“Chemistry and Technology of Lubricants”, Blackie Academic &Professional, London, 2^(nd) ed. 1997.

Preferred lubricant oil compositions have a viscosity, measured at 40°C. to ASTM D 445, in the range of 10 to 120 mm²/s, more preferably inthe range of 20 to 100 mm²/s. The kinematic viscosity KV₁₀₀ measured at100° C. is preferably at least 5.0 mm²/s, more preferably at least 5.2mm²/s and most preferably at least 5.4 mm²/s.

In a particular aspect of the present invention, preferred lubricant oilcompositions have a viscosity index determined to ASTM D 2270 in therange of 100 to 400, more preferably in the range of 125 to 325 and mostpreferably in the range of 150 to 250.

Furthermore, lubricant compositions for the use in the motor of thepresent invention may preferably comprise a High Temperature High Shear(HTHS) viscosity of at least 2.4 mPas, more preferably at least 2.6 mPasas measured at 150° C. according to ASTM D4683. According to a furtheraspect of the present invention the lubricant may preferably comprise ahigh temperature high shear of at most 10 mPas, especially at most 7mPas more preferably at most 5 mPas as measured at 100° C. according toASTM D4683. The difference between the High Temperature High Shear(HTHS) viscosities as measure at 100° C. and 150° C. HTHS₁₀₀-HTHS₁₅₀preferably comprises at most 4 mPas, especially at most 3.3 mPas andmore preferably at most 2.5 mPas. The ratio of the High Temperature HighShear (HTHS) viscosity measured at 100° C. (HTHS₁₀₀) to the HighTemperature High Shear (HTHS) viscosity measured at 150° C.(HTHS₁₅₀-HTHS₁₀₀/HTHS₁₅₀ preferably comprises at most at most 2.0 mPas,especially at most 1.9 mPas. High Temperature High Shear (HTHS)viscosity can be determined according to D4683.

In addition thereto, the lubricant useful as component of the presentmotor may comprises a high shear stability index (SSI). According to auseful embodiment of the present invention, the shear stability index(SSI) as measured according to ASTM D2603 Ref. B (12.5 minutes sonictreatment) could preferably amount to 35 or less, more preferably to 20or less. Preferably, lubricants comprising a shear stability index (SSI)as measured according to DIN 51381 (30 cycles Bosch-pump) of at most 5,especially at most 2 and more preferably at most 1 could be used.

The lubricant useful for the present invention can preferably bedesigned to meet the requirements of the SAE classifications asspecified in SAE J300. E.g. the requirements of the viscosity grades 0W,5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, and 60 (single-grade) and 0W-40,10W-30, 10W-60, 15W-40, 20W-20 and 20W-50 (multi-grade) could beadjusted.

Preferably, the lubricant composition meets the gasoline engine oilquality specifications ILSAC's GF-5, especially the emulsion retentionbench test stating that a mixture of formulated oil (80%), E85 fuel(10%), and water (10%) must form a stable emulsion for at least 24 hoursafter mixing at 0 and 25° C.

Consequently, the lubricant of the present invention may contain atleast about 1%, especially at least 5%, particularly at least 10% byvolume of water. Astonishingly, such high amounts of water do not impartunduly high lowering of the motor characteristics such as life time,cold run performance and fuel consumption.

Surprisingly, the present invention provides a lubricant forming highlystable emulsions with water. Therefore, a specific aspect of the presentinvention is the use of polymers having a high polarity as emulsionstabilizer in lubricants.

The invention will be illustrated in detail hereinafter with referenceto examples and comparative examples, without any intention that thisshould impose a restriction. Unless otherwise specified, the percentagesare weight percent.

PREPARATION EXAMPLES List of Abbreviations

MMA=methyl methacrylateN1214MA=methacrylic acid ester of NAFOL1214L125MA=methacrylic acid ester of LIAL125A1618MA=methacrylic acid ester of ALFOL 1620DMAEMA=dimethylaminoethyl methacrylateNVP=N-vinyl-2-pyrrolidonenDDM=n-dodecylmercaptontBPO=t-butylperoctoatetBPB=t-butylperbenzoate

Comparative Example 1

107.5 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 100° C. A mixture of 500 gramsof a L125MA, 8.5 grams of nDDM and 2 grams of tBPO was added to theround bottom flask via an addition funnel over the course of two hours.The temperature of the reaction mixture was maintained at 100° C.throughout the course of the addition. Following the complete ofaddition the mixture, the reaction mixture was held at 100° C. for anadditional 2 hours. Additional mineral oil was added to achieve thedesired concentration of polymer in oil.

Comparative Example 2

107.5 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 100° C. A mixture of 375 gramsof N1214MA, 125 grams of MMA, 7.5 grams of nDDM and 2 grams of tBPO wasadded to the round bottom flask via an addition funnel over the courseof two hours. The temperature of the reaction mixture was maintained at100° C. throughout the course of the addition. Following the complete ofaddition the mixture, the reaction mixture was held at 100° C. for anadditional 2 hours. Additional mineral oil was added to achieve thedesired concentration of polymer in oil.

Comparative Example 3

111 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 100° C. A mixture of 385 gramsof N1214MA, 100 grams of MMA, 15 grams of DMAEMA, 4.0 grams of nDDM and2 grams of tBPO was added to the round bottom flask via an additionfunnel over the course of two hours. The temperature of the reactionmixture was maintained at 100° C. throughout the course of the addition.Following the complete of addition the mixture, the reaction mixture washeld at 100° C. for an additional 2 hours. Additional mineral oil wasadded to achieve the desired concentration of polymer in oil.

Comparative Example 4

112.5 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 100° C. A mixture of 225 gramsof N1214MA, 275 grams of A1618MA, 5.0 grams of nDDM and 2 grams of tBPOwas added to the round bottom flask via an addition funnel over thecourse of two hours. The temperature of the reaction mixture wasmaintained at 100° C. throughout the course of the addition. Followingthe complete of addition the mixture, the reaction mixture was held at100° C. for an additional 2 hours. Additional mineral oil was added toachieve the desired concentration of polymer in oil.

Comparative Example 5

325 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 110° C. A mixture of 415 gramsof N1214MA, 70 grams of MMA, 15 grams of NVP and 5.0 grams of tBPO wasadded to the round bottom flask via an addition funnel over the courseof two hours. The temperature of the reaction mixture was maintained at110° C. throughout the course of the addition. Following the complete ofaddition the mixture, the reaction mixture was held at 110° C. for anadditional 2 hours. Additional mineral oil was added to achieve thedesired concentration of polymer in oil.

Example 1

325 grams of mineral oil were charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 100° C. A mixture of 485 gramsof N1214MA and 3.75 grams of tBPO was added to the round bottom flaskvia an addition funnel over the course of three hours. The temperatureof the reaction mixture was maintained at 100° C. throughout the courseof the addition. Following the complete of addition the mixture, thereaction mixture was held at 100° C. for an additional 2 hours. Thetemperature was raised to 130° C. and 15 grams of NVP was added to thereaction mixture with 2 grams of tBPB. The reaction mixture was held foran additional hour at 130° C. Additional mineral oil was added toachieve the desired concentration of polymer in oil.

Example 2

325 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 110° C. A mixture of 415 gramsof N1214MA, 70 grams of MMA and 5.0 grams of tBPO was added to the roundbottom flask via an addition funnel over the course of three hours. Thetemperature of the reaction mixture was maintained at 110° C. throughoutthe course of the addition. Following the complete of addition themixture, the reaction mixture was held at 110° C. for an additional 2hours. The temperature was raised to 130° C. and 15 grams of NVP wasadded to the reaction mixture with 2 grams of tBPB. The reaction mixturewas held for an additional hour at 130° C. Additional mineral oil wasadded to achieve the desired concentration of polymer in oil.

Example 3

325 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 110° C. A mixture of 210 gramsof N1214MA, 275 grams of A1618MA and 7.5 grams of tBPO was added to theround bottom flask via an addition funnel over the course of threehours. The temperature of the reaction mixture was maintained at 110° C.throughout the course of the addition. Following the complete ofaddition the mixture, the reaction mixture was held at 110° C. for anadditional 2 hours. The temperature was raised to 130° C. and 15 gramsof NVP was added to the reaction mixture with 2 grams of tBPB. Thereaction mixture was held for an additional hour at 130° C. Additionalmineral oil was added to achieve the desired concentration of polymer inoil.

Example 4

325 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 110° C. A mixture of 320 gramsof N1214MA, 160 grams of L125MA, 5 grams of MMA and 7.5 grams of tBPOwas added to the round bottom flask via an addition funnel over thecourse of three hours. The temperature of the reaction mixture wasmaintained at 110° C. throughout the course of the addition. Followingthe complete of addition the mixture, the reaction mixture was held at110° C. for an additional 2 hours. The temperature was raised to 130° C.and 25 grams of NVP was added to the reaction mixture with grams oftBPB. The reaction mixture was held for an additional hour at 130° C.Additional mineral oil was added to achieve the desired concentration ofpolymer in oil.

Example 5

325 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 110° C. A mixture of 475 gramsof N1214MA and 7.5 grams of tBPO was added to the round bottom flask viaan addition funnel over the course of three hours. The temperature ofthe reaction mixture was maintained at 110° C. throughout the course ofthe addition. Following the complete of addition the mixture, thereaction mixture was held at 110° C. for an additional 2 hours. Thetemperature was raised to 130° C. and 25 grams of NVP was added to thereaction mixture with 2 grams of tBPB. The reaction mixture was held foran additional hour at 130° C. Additional mineral oil was added toachieve the desired concentration of polymer in oil.

Example 6

325 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and wereheated under an atmosphere of nitrogen to 110° C. A mixture of 450 gramsof a N1214MA and 7.5 grams of tBPO was added to the round bottom flaskvia an addition funnel over the course of three hours. The temperatureof the reaction mixture was maintained at 110° C. throughout the courseof the addition. Following the complete of addition the mixture, thereaction mixture was held at 110° C. for an additional 2 hours. Thetemperature was raised to 130° C. and 50 grams of NVP was added to thereaction mixture with 2 grams of tBPB. The reaction mixture was held foran additional hour at 130° C. Additional mineral oil was added toachieve the desired concentration of polymer in oil.

Example 7

325 grams of mineral oil was charged to a four-neck round glass bottomflask equipped with glass stirrer, condenser and thermocouple and heatedunder an atmosphere of nitrogen to 110° C. A mixture of 425 grams ofN1214MA, 25 grams of MMA, 50 grams of NVP and 5.0 grams of tBPO wasadded to the round bottom flask via an addition funnel over the courseof two hours. The temperature of the reaction mixture was maintained at110° C. throughout the course of the addition. Following the complete ofaddition the mixture, the reaction mixture was held at 110° C. for anadditional 2 hours. Additional mineral oil was added to achieve thedesired concentration of polymer in oil.

Use Examples Emulsion Stability

1.0 grams of the experimental additive was mixed with 99.0 grams of anAPI Group I oil mixture having a kinematic viscosity of 5.4 cSt at 100°C. 80 mL of this blend of additive and oil was transferred to a 100 mLgraduated cylinder to which 10 mL of an ethanol/heptane (85/15 v/v)solution and 10 mL of water was added. This mixture was rapidly stirredfor 5 minutes and allowed to stand at room temperature for 24 hours. Apassing test was defined as the lack of a water layer after the end ofthe 24 hour period.

FTIR Spectroscopy

The additives were placed between silver chloride plates and sandwichedinto a Teflon cell holder. Using a Thermo Nicolet Avatar 370 FT-IR, theadditives were scanned 32 times at a resolution of 4 cm⁻¹. A backgroundscan was taken followed by the sample scan. The peak location of thedisubstituted amine, —CO—NR₂—, is observed as a shoulder peak to thestrong carbonyl, C═O, stretching peak.

TABLE 1 Additive compositions Comparative Examples Comparative ExampleNumber 1 2 3 4 5 Amount MMA — 25 20 — 14 of N1214MA — 75 77 45 83 mono-L125MA 100 — — — — mer A1618MA — — — 55 — DMAEMA — — 3 — — NVP — — — — 3% polymer 88 70 70 65 65 Mw, g/mol 25,000 40,000 100,000 75,000 90,000FTIR Analysis, cm⁻¹ n.o. n.o. n.o. n.o. 1696 Emulsion Stability FailFail Fail Fail Fail

TABLE 2 Additive compositions Examples Example Number 1 2 3 4 5 Amountof MMA — 14 — 1 — monomer N1214MA 97 83 42 64 88 L125MA — — — 32 —A1618MA — — 55 — 6 DMAEMA — — — — — NVP 3 3 3 3 5 % polymer 55 57 57 5857 Mw, g/mol 220,000 150,000 120,000 115,000 155,000 FTIR Analysis, cm⁻¹1691 1691 1691 1691 1690 Emulsion Stability Pass Pass Pass Pass PassExamples Example Number 6 7 Amount of MMA — 5 monomer N1214MA 90 85L125MA A1618MA — — DMAEMA — — NVP 10 10 % polymer 57 65 Mw, g/mol300,000 54,000 FTIR Analysis, cm⁻¹ 1696 1695 Emulsion Stability PassPass

The results in Tables 1 and 2 demonstrate that lubricant compositionscontaining copolymers as described by the invention are capable ofimproving the emulsion retention of a lubricant oil formulation.

In addition thereto, the properties of the present polymers have beentested using modified emulsion stability test.

The results in Table 3 were obtained when the concentration of exampleadditive was varied.

TABLE 3 Additional results from modified emulsion stability test* Amountof Emulsion Example Additive Stability 6 0.15 Pass 9 0.15 Pass

The results in Table 4 were obtained when example additives were mixedwith SAE 5W-30 engine oil.

TABLE 4 Additional results from modified emulsion stability test* Amountof Emulsion Example Additive Stability 8 0.15 Pass 9 0.15 Pass

1: A motor, comprising a lubricant composition, wherein the motor issuitable for a flexible-fuel vehicle or a dual-fuel vehicle and thelubricant composition comprises at least one ester group containingpolymer having a high polarity. 2: The motor according to claim 1,comprising a compression rate of at least 10:1. 3: The motor accordingto claim 1, comprising a fuel injection pump. 4: The motor according toclaim 1, comprising a multi valve. 5: The motor according to claim 1,wherein the motor meets a requirement of exhaust emission standard Euro5. 6: The motor according to claim 1, comprising an exhaust gasrecirculation. 7: The motor according to claim 1, comprising asecondary-air system. 8: The motor according to claim 1, wherein the atleast one ester group containing polymer is a statistical copolymercomprising at least 7% by weight of dispersing repeat units derived froma dispersing monomer. 9: The motor according to claim 8, wherein the atleast one ester group containing polymer is a statistical copolymercomprising at least 7% by weight of dispersing repeat units derived fromat least one heterocyclic vinyl compound. 10: The motor according toclaim 1, wherein the at least one ester group containing polymer is agraft copolymer having an nonpolar polymer as a graft base and adispersing monomer as a graft layer. 11: The motor according to claim10, wherein the at least one ester group containing polymer comprises atleast one heterocyclic vinyl compound as the graft layer. 12: The motoraccording to claim 11 wherein the at least one ester group containingpolymer is the graft copolymer comprising from 0.5 to 10% by weight ofdispersing repeat units derived from the at least one heterocyclic vinylcompound. 13: The motor according to claim 12, wherein the at least oneester group containing polymer is the graft copolymer comprising from 1to 5% by weight of dispersing repeat units derived from the at least oneheterocyclic vinyl compound. 14: The motor according to claim 1, whereinthe at least one ester group containing polymer has a —CO—NR₂— peak of1689 to 1692 cnf¹ as measured by FTIR spectroscopy. 15: The motoraccording to claim 1, wherein the at least one ester group containingpolymer is selected from the group consisting of a polyalkyl(meth)acrylate (PAMA), a polyalkyl fumerate, a polyalkyl maleate, and acombination thereof. 16: The motor according to claim 1, wherein the atleast one ester group containing polymer has a weight-average molecularweight of from 10 000 to 600 000 g/mol. 17: The motor according to claim1, wherein the at least one ester group containing polymer is a graftcopolymer comprising a graft base obtained by a process comprisingpolymerizing a monomer composition comprising: a) from 0 to 40% byweight, based on a weight of the monomer composition for preparing anonpolar segment, of an ethylenically unsaturated ester compound offormula (I):

wherein R is hydrogen or methyl, R¹ is a linear or branched alkylradical having 1 to 6 carbon atoms, and R² and R³ are each independentlyhydrogen or a group of formula —COOR′ in which R′ is hydrogen or analkyl group having 1 to 6 carbon atoms, b) from 5 to 100% by weight,based on the weight of the monomer composition for preparing thenonpolar segment, of an ethylenically unsaturated ester compound offormula (II):

wherein R is hydrogen or methyl, R⁴ is a linear or branched alkylradical having 7 to 15 carbon atoms, and R⁵ and R⁶ are eachindependently hydrogen or a group of the formula —COOR′ in which R″ ishydrogen or an alkyl group having 7 to 15 carbon atoms, c) from 0 to 80%by weight, based on the weight of the monomer composition for preparingthe nonpolar segment, of an ethylenically unsaturated ester compound offormula (III):

wherein R is hydrogen or methyl, R⁷ is a linear or branched alkylradical having 16 to 30 carbon atoms, and R⁸ and R⁹ are eachindependently hydrogen or a group of formula —COOR′″ in which R′″ ishydrogen or an alkyl group having 16 to 30 carbon atoms, and d) from 0to 50% by weight, based on the weight of the monomer composition forpreparing the hydrophobic segments, of a comonomer. 18: The motoraccording to claim 1, wherein the at least one ester group containingpolymer comprises at least one heterocyclic vinyl compound selected fromthe group consisting of 2-vinylpyridine, 3-vinylpyridine,2-methyl-5-vinylpyridine, 3-ethyl-4-vinylpyridine,2,3-dimethyl-5-vinylpyridine, vinylpyrimidine, vinylpiperidine,9-vinylcarbazole, 3-vinylcarbazole, 4-vinylcarbazole, 1-vinylimidazole,N-vinylimidazole, 2-methyl-1-vinylimidazole, N-vinylpyrrolidone,2-vinylpyrrolidone, N-vinylpyrrolidine, 3-vinylpyrrolidine,N-vinylcaprolactam, N-vinylbutyrolactam, vinyloxolane, vinylfuran,vinylthiophene, vinylthiolane, a vinylthiazole and a hydrogenatedvinylthiazole, a vinyloxazole, a hydrogenated vinyloxazole, and acombination thereof. 19: The motor according to claim 1, wherein thelubricant composition comprises at least one additional additive whichis not a polymer comprising an ester group having a high polarity. 20:The motor as claimed in claim 19, wherein the at least one additive is aviscosity index improver, a pour point improver, a dispersant, adetergent, a defoamer, a corrosion inhibitor, an antioxidant, anantiwear additive, an extreme pressure additive, a friction modifier, ora combination thereof. 21: The motor as claimed in claim 20, wherein theantiwear additive, the extreme pressure additive, or both is selectedfrom the group consisting of a phosphorous compound, a compoundcomprising sulfur and phosphorous, a compound comprising sulfur andnitrogen, a sulfur compound comprising elemental sulfur and¾S-sulfurized hydrocarbon, a sulfurized glyceride and a fatty acidester, an overbased sulfonate, a chlorine compound, graphite, molybdenumdisulfide, and a combination thereof. 22: A process for producing anemulsion stabilizer in a lubricant, comprising: contacting the lubricantwith a polymer comprising an ester group having a high polarity.